Conventional emotion detectors acquire and record data descriptive of a person's reaction to an event. Conventional emotion detectors also analyze the recorded data to interpret the person's emotional reaction to the event. The reactions recorded, analyzed, and interpreted by emotion detectors include a person's speech, facial expressions, physiological signals, device usage patterns, etc. To be effective, many emotion detectors require that the person exhibit a threshold level of activity. For example, emotion detectors based on a person's speech require that the person utter one or more detectable expressions. Similarly, emotion detectors based on device usage patterns require a person to manipulate an object (e.g., a mouse or keyboard) to establish a baseline usage pattern. Other emotion detectors require that sensors be in physical contact with a person to be effective. For example, emotion detectors based on a person's physiological state require that the person don one or more sensors (e.g., electrocardiogram electrodes, skin conductance sensors, etc.). Advantages introduced through the use conventional emotion detectors include a systemic ability to persistently record and later analyze a person's reaction to system-generated events.